1. Field of the Invention
The present invention relates to a curable polymer composition. More particularly, the present invention relates to a curable polymer composition which comprises an oxyalkylene base polymer having at least one silicon-containing group to the silicon atom of which a hydroxy group and/or a hydrolyzable group is bonded and which is cross linkable through formation of a siloxane bond (hereinafter referred to as a "silicon-containing reactive group").
2. Description of the Related Art
Oxyalkylene base polymers having the silicon-containing reactive groups are disclosed in U.S. Pat. No. 3,971,751, and one of typical examples of such polymers is a polymer of the formula: ##STR1## wherein X" is a hydrolyzable group such as a methoxy group.
The oxyalkylene base polymers having the silicon-containing reactive groups are cured through formation of siloxane bonds (Si--O--Si) between the polymer chains by the function of moisture in the air at room temperature to provide a rubbery cured material in the similar way to room temperature curable silicone rubbers. Since the cured material has good elongation properties, strength and adhesivity, it is used as a sealant, an adhesive and the like.
When the rubbery cured material is used as the sealant, it should satisfy various requirements, among which, the tensile properties and adhesivity to a substrate are important. The tensile properties include modulus, elongation, strength at break and the like, and often the rubbery cured material is required to have low modulus and large elongation, which are both characteristic properties of the rubber. The adhesivity includes bond strength and weather resistance of bond strength. The rubbery cured material is required to have large bond strength and good weather resistance of bond strength. Particularly when the rubbery cured material is used as a building sealant, it is often applied on a transparent material such as glass. Therefore, the weather resistance of bond strength, particularly the weather resistance under light illumination is important.
As a curable polymer composition which comprises the oxyalkylene base polymer having the silicon-containing reactive group and provides a cured material having low modulus, U.S. Pat. No. 4,788,254 discloses a curable polymer composition comprising said oxyalkylene base polymer, a compound having one silanol group in a molecule and/or a compound which generates a compound having one silanol group in a molecule when reacted with moisture (hereinafter referred to us "monovalent silanol compound" collectively).
To improve adhesivity of the cured material of the oxyalkylene base polymer having the silicon-containing reactive group, Japanese Patent Kokai Publication No. 182350/1982 discloses the use of a compound having a silicon atom to which a hydrolyzable group is bonded and an amino group such as .gamma.-aminopropyltrimethoxysilane [H.sub.2 NCH.sub.2 CH.sub.2 CH.sub.2 Si(OCH.sub.3).sub.3 ]or .gamma.-aminopropylmethyldimethoxysilane [H.sub.2 NCH.sub.2 CH.sub.2 CH.sub.2 Si(CH.sub.3)(OCH.sub.3).sub.2 ].
However, the composition comprising the silicon-containing compound having three hydrolyzable groups such as .gamma.-aminopropyltrimethoxysilane provides a cured material having large modulus. Even when such silicon-containing compound is used in combination with the monovalent silanol compound, the former deteriorates the effects of the latter. The composition comprising the silicon-containing compound having two hydrolyzable groups such as .gamma.-aminopropylmethyldimethoxysilane does not increase modulus of a cured material but the cured material has inferior weather resistance of bond strength.